Recently, rechargeable secondary batteries have widely been used as energy sources for wireless mobile devices. Also, the secondary batteries have attracted attention as power sources for electric vehicles (EV) and hybrid electric vehicles (HEV), which have been proposed to solve air pollution caused by conventional gasoline vehicles and diesel vehicles using fossil fuels.
Small-sized mobile devices use one or a few battery cells per device, while middle- or large-sized devices, such as automobiles, use middle- or large-sized battery modules in which a large number of battery cells are electrically connected or battery packs in which a plurality of battery modules are connected, due to the necessity for high-output large-capacity batteries.
The middle- or large-sized battery modules may be manufactured to have as small a size and weight as possible. Thus, the middle- or large-sized battery modules may be stacked with a high integration density, and prismatic batteries or pouch-type batteries having a small weight to capacity ratio are mainly used as battery cells applied to the middle- or large-sized battery modules.
In particular, a pouch-type battery cell using an aluminum laminate sheet as an external member has lately attracted considerable attention due to advantages, such as a small weight, low manufacturing costs, and easy shape deformation.
In order for the middle- or large-sized battery modules to provide output and capacity required by a predetermined apparatus or device, a plurality of battery cells should be electrically connected in series, parallel, or a combination of series and maintain a stable structure against external force.
Since the middle- or large-sized battery module has a structure into which a plurality of battery cells are combined, when some of the battery cells suffer over-voltage, over-current, or over-heat, a sensing unit configured to sense and control the over-voltage, over-current, or over-heat is necessarily required. The sensing unit should be stably connected to the battery cells to provide reliable voltage/current information to a BMS.
In an example, a conventional battery module includes a cell cartridge assembly including battery cells and stacking cartridges configured to stack the battery cells. The cell cartridge assembly may be arranged in layers. The sensing unit may be coupled to one side of the cell cartridge assembly arranged in layers. A hook fastening method is frequently applied for the convenience of assembly.
However, in a battery module using the hook fastening method, the sensing unit is highly likely to be damaged during a hook fastening process, and there may be clearance in a hook-fastened portion due to tolerance, so that a fixed state of the sensing unit may become unstable.
Meanwhile, since the middle- or large-sized battery modules applied to automobiles are easily exposed to vibration and impact, the middle- or large-sized battery modules should have high structural and electrical stability. However, the conventional battery module has weak durability against impact and vibration because the fixed state of the sensing unit is unstable as described above.